The invention relates to a device for forming mineral fibers by an internal centrifuging method. It applies in particular to the industrial production of glass wool that is intended to be used, for example, in the composition of thermal and/or acoustic insulation products.
Different internal centrifuging methods are known. A molten glass thread is introduced into a fiberizing spinner rotating at high speed and pierced at its periphery by a very great number of orifices through which the glass is sprayed in the form of filaments under the effect of the centrifugal force. These filaments can then be subjected to the action of an annular drawing current at high temperature and speed along the wall of the centrifuge, a current that thins them and transforms them into fibers. The fibers that are formed are driven by this gaseous drawing current to a receiving device generally consisting of a gas-permeable receiving and conveying mat.
This method has been the subject of numerous refinements, relating in particular, for some, to the fiberizing spinner, for others, to the means of generating the annular drawing current, for example by the use of burners of particular type. See in particular the documents EP-B-0 189 354, EP-B-0 519 797, WO-A-97/15532 regarding the latter point.
The document FR-A-1 382 917 describes a fiberizing member, the principle of which is still abundantly used: the molten material is brought into a basket comprising, on its vertical wall, orifices through which the material is sprayed onto the wall of a fiberizing spinner which is attached to the basket and which comprises a large number of orifices. This wall is called the “strip” of the fiberizing spinner. In order to obtain quality fiber production, the orifices are distributed on annular rows and the diameters of the orifices are variable depending on the row to which they belong, this diameter decreasing from the top of the strip to its bottom part.
Enhancements have been made to this basic principle, as taught in particular in the document FR-A-2 443 436, in which means make it possible to obtain a laminar flow of the molten material from top to bottom of the strip of the spinner.
Another modification, described in the document EP-A-1 370 496, has been made to enhance the quality of the fibers and increase the efficiency. This modification entails distributing the orifices of the strip in a plurality of annular areas arranged one above the other, with at least two annular areas having a number of orifices per unit of surface area which is different by a value greater than or equal to 5%.
The document WO 03/069226 describes an internal combustion burner comprising a combustion chamber into which opens at least one fuel and oxidant feed duct and at least one flame stabilizing element creating a containment area in which at least a portion of the combustion takes place.
In all these examples, the peripheral strip of the spinner is heated both by the molten glass which is centrifuged in the fiberizing spinner and by the hot air blown by an internal combustion burner generating the annular drawing current.
However, the heating by an internal combustion burner is a source of significant energy consumption, with an energy efficiency less than 30%, and a source of very high carbon dioxide emissions.